In a total knee arthroplasty (TKA) procedure, a patient's distal femur is resected and replaced with a prosthetic femoral implant, and the patient's proximal tibia is resected and replaced with a prosthetic tibial implant. The prosthetic femoral implant articulates with the prosthetic tibial implant to restore joint motion.
Many factors influence joint motion after the TKA procedure. The size and shape of each prosthetic implant will impact joint motion. Additionally, the location and orientation of each prosthetic implant, which is determined by the location and orientation of the corresponding bone resections, will impact joint motion. The tension or laxity of the surrounding soft tissue will also impact joint motion. For example, if the surrounding collateral ligaments are too tense, joint motion may be limited, but if the surrounding collateral ligaments are too lax, improper femoral rotation or femoral lift-off may occur. Also, the soft tissue balance around the joint will impact joint motion.
Different surgical philosophies have traditionally influenced TKA instruments and procedures. For example, a first, “measured resection” philosophy emphasizes bone resections while preserving the natural joint axis and soft tissue. A second, “soft tissue balancing” philosophy emphasizes soft tissue modifications while preserving bone.
The present invention provides an exemplary TKA instrument and procedure. The instrument separates the patient's tibia and femur, in both extension and flexion, to place the knee joint in tension and to measure a gap and an angle therebetween. The instrument includes various modular accessories. The accessories provide flexibility of usage throughout the TKA procedure. For example, the instrument may be used before resecting or otherwise manipulating the patient's knee joint to evaluate the natural knee joint and plan the TKA procedure, as well as after resecting or otherwise manipulating the patient's knee joint to evaluate and/or further plan the TKA procedure. The accessories also allow each individual user to select accessories that accommodate his or her own surgical philosophy and the needs of the particular patient. The accessories also allow the user to incorporate multiple surgical philosophies into a single surgical procedure, such as by comparing the potential outcome of one accessory with the potential outcome of another accessory.
According to an embodiment of the present invention, a knee arthroplasty instrument is provided for use in a patient's knee joint. The knee joint includes a tibia and a femur. The instrument may include a tensioning tool, a first sizer, and a second sizer different from the first sizer. The tensioning tool includes a tibial component configured for placement against the tibia and a femoral component configured for placement against the femur, the femoral component being movably coupled to the tibial component to place the patient's knee joint in tension by separating the tibia and the femur. The first sizer is removably coupled to the tensioning tool, the first sizer including at least one first reference indicator that references the femur to locate a cut guide relative to the femur. The second sizer is different from the first sizer and is removably coupled to the tensioning tool, the second sizer including at least one second reference indicator that references the femur to locate the cut guide relative to the femur.
According to another embodiment of the present invention, a knee arthroplasty instrument is provided for use in a patient's knee joint. The knee joint includes a tibia and a femur. The instrument may include a tensioning tool, a cut guide, and a sizer. The tensioning tool includes a tibial component configured for placement against the tibia and a femoral component configured for placement against the femur, the femoral component being movably coupled to the tibial component to place the patient's knee joint in tension by separating the tibia and the femur. The cut guide is removably coupled to the tensioning tool. The sizer is removably coupled to the tensioning tool to locate the cut guide relative to the femur.
According to yet another embodiment of the present invention, a knee arthroplasty method is provided for a patient's knee joint. The knee joint includes a tibia and a femur. The method may include: using a tensioning tool to place the patient's knee joint in tension by separating the tibia and the femur; selecting one of a first sizer and a second sizer, the first sizer differing from the second sizer; coupling the selected sizer to the tensioning tool; and using the selected sizer to locate a cut guide relative to the femur.
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate exemplary embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner.